POS0737 AGE AND SEX BIAS OF ULTRASOUND SCORES FOR DIAGNOSIS OF GIANT CELL ARTERITIS: INSIGHTS FROM THE PROSPECTIVE, LONGITUDINAL HAS-GCA STUDY
Authors: K. Van der Geest, A. Sebastian, E. Conticini, S. Inness, J. Jackson, A. Kayani, M. Khurshid, G. Klinowski, P. Macchioni, D. Prieto-Peña, C. Salvarani, M. Tariq, A. Tomelleri, B. Dasgupta
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Giant cell arteritis (GCA) is an age-linked, critically ischaemic vasculitis where ultrasound (US) serves as an important tool enabling urgent diagnosis and therapy. US scores have been developed to quantify the arterial inflammation in GCA [1,2], but optimal diagnostic cut-off points and potential bias of age and sex on these values remain un-elucidated. <h3>Objectives</h3> To compare the diagnostic accuracy of previously reported US scores for GCA, and to determine whether these scores require correction for age and sex. <h3>Methods</h3> The HAS-GCA study, with a prospective, multicentre, cohort design, recruited 229 consecutive patients with suspected, new-onset GCA from 7 sites located in the UK, Italy, Spain and the Netherlands. All cases underwent bilateral US evaluation of the three temporal artery segments (common superficial, parietal, frontal) and axillary arteries. Intimal-medial thickness (IMT) was measured in each segment. Three ultrasound scores were calculated based on the IMT: halo count (HCount) [1], Halo Score (HScore) [2] and the OMERACT GCA US Score (OGUS) [2]. The definition of halo was based on previously reported IMT cut-off values [3]. The reference standard was the final clinical diagnosis after 6 months follow-up. ROC with AUC analysis was performed. Optimal cut-off points were determined by Youden Index. Group comparisons were made by Mann Whitney U test and correlations by Spearman's rank correlation coefficient. P values &lt; 0.05 were considered statistically significant. <h3>Results</h3> A final diagnosis of GCA was made in 84 patients, whereas 145 cases received an alternative diagnosis (i.e. non-GCA patients). HCount, HScore and OGUS were significantly higher in GCA patients than non-GCA patients. In non-GCA patients, all three scores were significantly higher in men than women, and showed a statistically significant, positive correlation with age. In GCA patients, the US scores showed a positive correlation (HCount and OGUS) or strong trend for a positive correlation (HScore) with age; and the HCount was significantly higher in men. All scores effectively discriminated GCA from non-GCA patients as indicated by ROC analysis: AUC for halo count 0.936 (0.899-0.974), Halo Score 0.894 (0.848-0.939) and OGUS 0.937 (0.902-0.973). The optimal diagnostic cut-off points were: 2 for HCount (sens 86%, spec 92%), 17 for HScore (sens 76%, spec 91%) and 0.80 for OGUS (sens 87%, spec 93%). These diagnostic cut-off points differed in sensitivity and specificity within different age- and sex-defined groups with the highest sensitivity and lowest specificity observed among old (&gt;81yr) male patients. Alternatively, age- and sex-stratified cut-off points could be established for the US scores (Table 1). <h3>Conclusion</h3> All previously reported US scores show excellent diagnostic accuracy for GCA, but are prone to over-diagnose GCA in older males. Our data highlight the need for age- and sex-specific diagnostic cut-off points. The excellent comparative performance of the simple HCount in GCA diagnosis suggests an exciting role in future clinical practice. <h3>References</h3> [1]van der Geest KSM, et al. Annals of the Rheumatic Diseases 2020 Mar;79(3):393-399. [2]Dejaco C, et al. Annals of the Rheumatic Diseases 2022 doi: 10.1136/ard-2022-223367 [3]Schafer VS, et al. Rheumatology 2017 Sep 1;56(9):1632. <h3>Acknowledgements</h3> K. van der Geest and A. Sebastian share first authorship. <h3>Disclosure of Interests</h3> Kornelis van der Geest Speakers bureau: Roche, Grant/research support from: AbbVie, Alwin Sebastian: None declared, Edoardo Conticini: None declared, Sue Inness: None declared, Jo Jackson: None declared, Abdul Kayani: None declared, Muhammad Khurshid: None declared, Giulia Klinowski: None declared, Pierluigi Macchioni: None declared, Diana Prieto-Peña: None declared, Carlo Salvarani: None declared, Mohammad Tariq: None declared, Alessandro Tomelleri: None declared, Bhaskar Dasgupta Consultant of: Roche, Chugai, Sanofi, Grant/research support from: Roche, Sanofi, AbbVie, and GlaxoSmithKline.